The present invention relates to a temperature adjustment apparatus in, e.g., an alignment stage apparatus such as an exposure apparatus or a high-precision processing apparatus requiring precise alignment, an exposure apparatus having the temperature adjustment apparatus, and a semiconductor device manufacturing method.
A projection exposure apparatus (e.g., a stepper or the like) used in photolithography for manufacturing a semiconductor element, liquid crystal display element, or the like, transfers at a high precision a pattern formed on a master such as a reticle or photomask onto a substrate such as a wafer or glass plate coated with a photoresist via a projection optical unit. For this purpose, very high imaging characteristics are demanded for the projection optical unit, and a high measurement precision is demanded for, e.g., a laser interferometer for measuring the alignment of a stage which supports a substrate such as a master or wafer.
The imaging characteristics of the projection optical unit and the measurement precision of the laser interferometer are greatly influenced by changes in apparatus and ambient temperatures. The laser interferometer causes fluctuations of a laser beam upon a change in ambient temperature, degrading the measurement precision.
At the same time, a member holding a mirror as a measurement target of the laser interferometer deforms owing to the temperature change, the relative alignment of a substrate and the mirror serving as an alignment reference change, and the measurement precision decreases. Recently, demands have arisen for an alignment precision of a nanometer (nm) order. For example, even if a 100-mm thick low-temperature thermal expansion member (thermal expansion coefficient: 1xc3x9710xe2x88x926) deforms by 100 nm upon a temperature change of 1xc2x0 C., and the air temperature on the laser path of the laser interferometer changes by 1xc2x0 C., the alignment measurement value may change by 100 nm depending on conditions. Hence, the temperatures of the building components of the projection exposure apparatus and its ambient temperature must be kept constant.
In a conventional projection exposure apparatus, a temperature rise of the apparatus by a heating member such as an exposure light source or a driving motor for driving a stage degrades the measurement precision of, e.g., the laser interferometer for measuring the stage alignment and the imaging characteristics of the projection optical unit.
In some cases, a temperature change of air changes the ambient temperature of the projection exposure apparatus, degrading the imaging characteristics of the projection optical unit. To prevent this, global air-conditioning is generally performed in which the projection exposure apparatus is stored in an environment control chamber, and temperature-controlled air is supplied into the chamber.
An exposure apparatus requiring precise temperature management undergoes temperature management by a combination of global air-conditioning and a method of directly supplying a temperature-controlled coolant such as air or water to a portion to be cooled. For example, to keep the measurement precision of the laser interferometer constant, air controlled to a predetermined temperature in a predetermined direction is supplied into a local space in the optical path of a laser beam between the laser interferometer and a mirror for reflecting a laser beam from the laser interferometer. To recover and remove heat generated by, e.g., a driving motor for driving a reticle stage or wafer stage, a cooling circulation pipe surrounds the driving motor, and a coolant such as water, air, or an inert liquid is circulated from an external temperature adjustment apparatus to the circulation pipe.
The temperature is controlled by setting a temperature sensor at or near a portion to be temperature-controlled, changing the flow rate or temperature of a coolant on the basis of an output from the temperature sensor, and adjusting the heat recovery amount (see Japanese Patent Laid-Open Nos. 7-302124 and 7-302747).
FIG. 14 is a view schematically showing an example of the driving device of an alignment stage in a conventional exposure apparatus. A wafer 501 is held by a top plate 503 of an alignment stage via a wafer chuck 502. A pattern formed on a master (not shown) such as a reticle is transferred onto the wafer 501 by irradiation light from an illumination optical unit (not shown) via a projection lens (not shown). The alignment stage aligns the wafer by relatively moving linear motors made up of a movable element 505 to which permanent magnets 506 are fixed and a stationary element 507 in which a plurality of coils 508 are buried, in accordance with driving signals from a controller 511 and driver 512. The movable element 505 is guided by hydrostatic bearings 524 and connected to linear motors 526 for vertical movement. The top plate 503 is set via the movable element 505 and linear motors 526. The stationary element 507 has a plurality of coils 508 and is constituted by a jacket structure so as to flow a coolant for recovering heat generated by the coils 508.
A mirror 504 is attached to the top plate 503, and the alignment of the top plate 503 is measured by an alignment measurement unit 516 such as a laser interferometer fixed to an alignment position where the unit 516 faces the mirror 504. A measurement value from the alignment measurement unit 516 is sent to the controller 511. The controller 511 controls the energization amount to the coil 508 of each linear motor via the driver 512 on the basis of the measurement value, drives and controls the linear motor, and drives and aligns the alignment stage at a high precision.
The stationary element 507 is connected to a coolant pipe 518 for circulating a coolant temperature-managed by a cooling unit 517, in order to prevent heat generated by each coil 508 upon driving the linear motor from conducting to air or a member and increasing the temperatures of the top plate 503 and wafer 501. The temperature-managed coolant drains heat generated by the coil 508 and is recovered by the cooling unit 517 outside the driving device. To compensate for the temperature, a temperature control unit 513 receives temperature data from a temperature measurement unit 515 for outputting temperature data measured by a temperature sensor 514 set on the movable element 505, and instructs the cooling unit 517 to control the temperature or flow rate of the coolant so as to minimize temperature changes of the movable element 505 and top plate 503. In addition, the temperature control unit 513 supplies to the linear motors via the coolant pipe 518 a coolant which is managed in temperature and adjusted in flow rate by the cooling unit 517. The temperature-managed coolant absorbs heat generated by the linear motor stationary element 507, and suppresses temperature changes of the movable element 505, top plate 503, and wafer 501.
In this prior art, to precisely manage the temperatures of a plurality of heating portions, {circle around (1)} a necessary amount of coolant temperature-controlled in accordance with the respective heating portions is supplied to the heating portions, or {circle around (2)} a coolant of the same temperature is supplied to all the heating portions after the flow rate is secured such that the coolant temperature after absorbing heat generated by all the heating portions is equal to or smaller than the allowable rise temperature of the apparatus. In {circle around (1)}, the pipe for supplying the coolant is complicated. Particularly to manage the temperature of the wafer stage or the like, problems such as a load resistance to driving due to the pipe rigidity and a location ensured to lay out the pipe must be solved. For example, to individually control the temperatures or flow rates of the respective linear motors when the linear motors have different driving patterns, the number of cooling units must be increased as the number of linear motors increases. Also, the number of coolant pipes extending from the cooling units to the alignment stage increases.
However, the number of pipes and their diameter are limited because a disturbance to alignment caused by the flexural rigidity or vibrations of the pipe must be suppressed. It is not, therefore, practical to arrange cooling units equal in number to the linear motors, individually lay out pipes from the respective cooling units to the respective linear motors, and control coolant amounts to the respective linear motors. For this reason, a given number of linear motors is set as one group, like {circle around (2)}, and controlled at the same coolant temperature or flow rate by using one cooling unit. It is difficult to execute precise temperature control for each linear motor. In this method, the cooling amount of the coolant is determined in correspondence with a portion having the largest heat generation amount, and an unwanted cooling amount (flow rate or temperature) of the coolant is inefficiently supplied to another heating portion having a small heat generation amount.
To rapidly cope with a change in the heat amount of a heating element such as a coil, there is proposed a method of predicting the heat amount of the heating element by a temperature control unit and controlling the heat recovery amount of a coolant. The coolant pipe extending from the cooling unit 517 to each linear motor is as long as 5 m or more. Thus, (1) even if the coolant temperature is controlled, a long time is taken to reflect the coolant temperature on each linear motor, and temperature control is delayed. (2) Even if the coolant temperature is controlled by the cooling unit 517 at a high precision, a high-precise temperature is not reflected when the coolant reaches the linear motor owing to movement of heat during a long pipe. (3) A large time lag occurs because the cooling unit 517 cannot change the coolant temperature as fast as an output from the linear motor. These problems make it difficult to perform high-precision temperature control for objects to be temperature-controlled such as a top plate and a substrate including a wafer to be aligned.
If the temperature is controlled based on an output from the temperature sensor, the output from the temperature sensor is changed after the temperature changes, so high-response temperature control cannot be achieved as a whole. Furthermore, attaching the temperature sensor increases cost and decreases reliability.
As an output from a recent exposure apparatus increases, the heat amount of each driving portion increases. It becomes difficult for the conventional method to ensure a coolant flow rate at which all generated heat is recovered and a temperature rise of a coolant is suppressed to be smaller than the allowable temperature difference of the apparatus. In other words, to ensure a high coolant flow rate, the pipe must be made thick under limitations on the pump ability or the like. Such a pipe is difficult to lay out. In addition, the thick pipe acts as a nonlinear driving load resistance with respect to an alignment driving portion and degrades the alignment precision.
Vibrations caused by the flow of a coolant along with an increase in coolant flow rate cannot be ignored and may adversely influence an alignment precision, which must be high. A coolant having a large heat capacity may be used to recover generated heat without excessively increasing the coolant flow rate. However, there is no coolant having a heat capacity with which heat generated by the driving unit of the exposure apparatus or the like can be recovered at a proper flow rate.
As described above, heat generated in the exposure apparatus has conventionally been recovered to suppress a temperature rise in order to suppress a temperature change in the apparatus. If heat generated in the entire exposure apparatus increases, the conventional method cannot completely recover the generated heat, and each portion of the apparatus inevitably changes in temperature. Even if generated heat can be completely recovered, the alignment precision degrades, which is in conflict with the purpose of increasing the alignment precision.
The present invention has been proposed to solve the conventional problems, and has as its object to provide a temperature adjustment apparatus capable of controlling the temperature of an exposure apparatus or the like at a high precision with a simple arrangement and high response, to provide a high-precision, high-reliability exposure apparatus which suppresses changes in apparatus and ambient temperature even if heat generated in the apparatus increases along with an increase in output of the entire exposure apparatus, and suppresses decreases in alignment measurement precision, alignment precision, and imaging characteristics caused by a temperature change, and to provide a semiconductor device manufacturing method.
To achieve the above object, according to the present invention, there is provided a temperature adjustment apparatus for adjusting a temperature of an object to be temperature-controlled, comprising a first temperature adjustment mechanism for controlling the temperature of the object to be temperature-controlled, and a second temperature adjustment mechanism for controlling the temperature of the object to be temperature-controlled, wherein the first and second temperature adjustment mechanisms have different temperature control responses, and control the temperature of the object to be temperature-controlled in cooperation with the coarse adjustment and fine adjustment on the basis of a difference in response.
In the temperature adjustment apparatus of the present invention, the object to be temperature-controlled preferably includes an actuator or a member near the actuator.
In the temperature adjustment apparatus of the present invention, the object to be temperature-controlled may include a plurality of objects to be temperature-controlled. The second temperature adjustment mechanism can serially connect the plurality of objects to be temperature-controlled and adjust temperatures. Also, the second temperature adjustment mechanism can adjust, in parallel, temperatures of the plurality of objects to be temperature-controlled.
In the temperature adjustment apparatus of the present invention, the first temperature adjustment mechanism preferably controls the temperature of the object to be temperature-controlled on the basis of prediction of the temperature of the object to be temperature-controlled. The first temperature adjustment mechanism preferably comprises a Peltier element arranged at or near the object to be temperature-controlled.
In the temperature adjustment apparatus of the present invention, the second temperature adjustment mechanism preferably recovers heat of the object to be temperature-controlled by using a coolant temperature-controlled by a cooling unit.
In the temperature adjustment apparatus of the present invention, the first temperature adjustment mechanism preferably comprises a third temperature adjustment mechanism for adjusting a temperature of a heat exhaust portion. The third temperature adjustment mechanism can serve as part of the second temperature adjustment mechanism.
According to the present invention, there is provided a temperature adjustment apparatus for adjusting temperatures of a plurality of objects to be temperature-controlled, comprising a plurality of first temperature adjustment mechanisms which are respectively arranged at the plurality of objects to be temperature-controlled and respectively control the temperatures of the objects to be temperature-controlled, and a second temperature adjustment mechanism for recovering heat exhausted from the plurality of first temperature adjustment mechanisms at once.
In the temperature adjustment apparatus of the present invention, the objects to be temperature-controlled preferably include actuators or members near the actuators.
In the temperature adjustment apparatus of the present invention, the first temperature adjustment mechanisms preferably control the temperatures of the objects to be temperature-controlled on the basis of prediction of the temperatures of the objects to be temperature-controlled. The first temperature adjustment mechanisms preferably comprise Peltier elements respectively arranged at the objects to be temperature-controlled.
In the temperature adjustment apparatus of the present invention, the second temperature adjustment mechanism preferably adjusts temperatures of heat exhaust portions of the first temperature adjustment mechanisms.
According to the present invention, there is provided an alignment stage apparatus, comprising a first temperature adjustment mechanism for controlling a temperature of an object to be temperature-controlled, a second temperature adjustment mechanism for controlling the temperature of the object to be temperature-controlled, the first and second temperature adjustment mechanisms having different temperature control responses, and an actuator for controlling the temperature of the object to be temperature-controlled in cooperation with coarse adjustment and fine adjustment on the basis of a difference in response, and driving the alignment stage by using information about the temperature control as one piece of information for driving control.
According to the present invention, there is provided an exposure apparatus having an illumination optical unit for emitting exposure light, a stage for supporting a substrate, and a main controller for controlling exposure operation of transferring a pattern formed on a master to the substrate, comprising a controller for controlling a Peltier element on the basis of an operation control signal from the main controller, and controlling heat movement by the Peltier element, the Peltier element being set at or near an object to be temperature-controlled.
In the exposure apparatus of the present invention, the controller preferably predicts a heat generation amount or temperature of the object to be temperature-controlled on the basis of the operation control signal from the main controller, and controls the Peltier element.
In the exposure apparatus of the present invention, a heat recovery unit is preferably arranged near the object to be temperature-controlled. The heat recovery unit preferably uses a coolant whose temperature and flow rate are controlled by a cooling unit.
In the exposure apparatus of the present invention, the controller preferably predicts a heat generation amount or temperature of the object to be temperature-controlled on the basis of the operation control signal from the main controller, and controls the Peltier element and/or a heat recovery unit. It is preferable that the main controller include a driving controller for controlling an actuator of the stage, and that the controller control the Peltier element and/or a heat recovery unit on the basis of a stage driving signal from the driving controller.
In the exposure apparatus of the present invention, it is preferable that at least one temperature sensor for measuring a temperature of the object to be temperature-controlled be set, and that the controller control the Peltier element and/or a heat recovery unit on the basis of an output signal from the temperature sensor.
In the exposure apparatus of the present invention, when the object to be temperature-controlled includes a heating element, a heat conduction path between the heating element and the Peltier element is preferably formed from a material higher in thermal conductivity than a material of a non-heat conduction path. The Peltier element is preferably sandwiched between the object to be temperature-controlled and a base member, and the base member is preferably formed from a material having a high thermal conductivity and a large heat capacity.
According to the present invention, there is provided an exposure apparatus having an illumination optical unit for emitting exposure light, a stage for supporting a substrate, and a main controller for controlling exposure operation of transferring a pattern formed on a master to the substrate, comprising a heat generation amount controller for controlling a heat generation amount of a heating element in accordance with an operation status of the exposure apparatus, the heating element being set near at least part of an object to be temperature-controlled.
In the exposure apparatus of the present invention, the heating element is preferably set near a heating element of the object to be temperature-controlled.
When the exposure apparatus of the present invention comprises a linear motor with a plurality of coils as actuators of the stage, a coil not participating in the exposure operation can be used as the heating element. An actuator of the stage can include actuators larger by at least one than at least one degree of freedom, and each of the actuators can be used as the heating element.
In the exposure apparatus of the present invention, a heat recovery unit for recovering a heat generation amount or adjusting a temperature is preferably disposed near the object to be temperature-controlled. The heat recovery unit can use a coolant whose temperature and flow rate are controlled by a cooling unit. The heat recovery unit is preferably controlled based on the heat generation amount of the heating element.
In the exposure apparatus of the present invention, the heat generation amount controller preferably controls the heat generation amount of the heating element on the basis of a heat generation amount recovered by a heat recovery unit. The heat generation amount controller preferably sets an initial heat generation amount for the heating element. The initial heat generation amount can be set from a difference between a maximum heat generation amount generated from a heating element of the object to be temperature-controlled and a maximum heat recovery amount of a heat recovery unit.
In the exposure apparatus of the present invention, the heat generation amount controller preferably controls the heat generation amount of the heating element on the basis of an exposure signal from the main controller. The heat generation amount controller preferably predicts a heat generation amount or temperature of the exposure apparatus on the basis of an exposure signal from the main controller, and controls the heat generation amount of the heating element so as to reduce a temperature change of the exposure apparatus.
In the exposure apparatus of the present invention, it is preferable that at least one temperature sensor for measuring a temperature of the object to be temperature-controlled be set, and that the heat generation amount controller control the heat generation amount of the heating element on the basis of an output signal from the temperature sensor.
In the exposure apparatus of the present invention, it is preferable that the main controller include an exposure amount controller for controlling an exposure amount of the illumination optical unit, and that the heat generation amount controller control the heat generation amount of the heating element on the basis of a signal from the exposure amount controller.
In the exposure apparatus of the present invention, the exposure apparatus preferably further comprises a display, a network interface, and a computer for executing network access software, and maintenance information of the exposure apparatus is communicated via a computer network.
The network access software preferably provides on the display a user interface for accessing a maintenance database provided by a vendor or user of the exposure apparatus, and enables obtaining information from the database via the internet or a dedicated network connected to the computer network.
According to the present invention, there is provided a semiconductor device manufacturing method comprising the steps of installing manufacturing apparatuses for performing various processes, including the above-described exposure apparatus, in a semiconductor manufacturing factory, and manufacturing a semiconductor device in a plurality of processes by using the manufacturing apparatuses.
The device manufacturing method of the present invention preferably further comprises the steps of connecting the manufacturing apparatuses by a local area network, and communicating information about at least one of the manufacturing apparatuses between the local area network and the Internet or a dedicated network serving as an external network of the semiconductor manufacturing factory. It is preferable that a database provided by a semiconductor device manufacturer or a supplier of the exposure apparatus be accessed by data communication via the external network to obtain maintenance information of the manufacturing apparatus, or production management be done by data communication between the semiconductor manufacturing factory and another semiconductor manufacturing factory via the external network.
According to the present invention, there is provided a semiconductor manufacturing factory comprising manufacturing apparatuses for performing various processes, including the above-described exposure apparatus, a local area network for connecting the manufacturing apparatuses in the semiconductor manufacturing factory, and a gateway for enabling accessing the Internet or a dedicated network serving as an external network of the semiconductor manufacturing factory from the local area network, wherein information of at least one of the manufacturing apparatuses can be communicated.
According to the present invention, the Peltier element near the object to be temperature-controlled is controlled based on exposure operation of an exposure apparatus or the like. This enables heat movement control with good response with respect to the exposure operation, and enables high-precision temperature control which cannot be achieved by the prior art. Since a temperature sensor need not always be employed, a low-cost exposure apparatus with high stability can be implemented. Further, decreases in alignment measurement precision and alignment precision by a temperature change can be suppressed.
The heat recovery unit is arranged near the object to be temperature-controlled. A heat movement amount controlled by the Peltier element can be reduced, the control efficiency of the Peltier element can be increased, and heat generated by the Peltier element itself can be suppressed to be small. As a result, an increase in total heat amount to be recovered can be suppressed.
The heat conduction path between the Peltier element and a heating element is made of a material having a high thermal conductivity. Therefore, the heat movement amount between the Peltier element and the heating element can be increased, and the heat amount of the object to be temperature-controlled can be efficiently controlled. The base member is made of a material having a high thermal conductivity or large heat capacity, so that a heat amount from the object to be temperature-controlled can suppress temperature nonuniformity or a temperature rise of the base member.
The heat generation amount of a heating unit near the object to be temperature-controlled is controlled. Thus, a change in the heat generation amount of the object to be temperature-controlled can be reduced to reduce a change in temperature at each portion of the apparatus and a change in ambient temperature. The heating unit is set near a heating element for the object to be temperature-controlled. The heating unit can give influence equal to influence of the heating element of the driving device on another portion, which facilitates temperature control of each portion of the apparatus.
When a linear motor having a plurality of coils is used as a stage driving unit, a coil not participating in exposure operation or the like is used as a heating unit, and no new heating unit need be arranged. Moreover, two or more driving units are arranged in one driving direction, and the driving force and heat generation amount in this driving direction are arbitrarily changed. With this arrangement, each driving unit can be used as a heating unit, and no new heating unit need be arranged, which is advantageous in terms of installation space and cost.
The heat recovery unit is adopted together with control of the heat generation amount of the heating unit. Even if the heat generation amount of each driving portion increases along with an increase in output from the entire apparatus, temperature changes of the apparatus and atmosphere can be suppressed. A temperature change can be controlled at a relatively low temperature, and decreases in measurement precision and alignment precision by a temperature change can be suppressed.
The heat generation amount of the heating unit is controlled on the basis of exposure operation of the exposure apparatus and a heat generation amount recovered by the heat recovery unit. The heating state of the apparatus can be accurately grasped, and thus the heat generation amount can be appropriately controlled. By predicting a temperature rise of each portion of the apparatus on the basis of various pieces of information, a proper heat generation amount can be applied to the heating unit, and temperature control can be minimized.
By reflecting the detection result of the temperature at each portion of the apparatus on the heating unit, higher-precision control of a temperature change can be achieved.
Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the figures thereof.